Telephone-transmitter



, (NO Model.) 2 Sheets-Sheet 1.

W53. COLE. TELEPHONE TRANSMITTER.

Patented Apia 14-, 1896. I

(No Model.) 2 Sheets-Sheet 2.

W. RLOOLE. TELEPHONE TRANSMITTER.

No. 558,354. PatentedApr. .14, 1896-.

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UNITED STATES PATENT OFFICE.

NVILLIAM R. COLE, OF DETROIT, MICHIGAN.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 558,354, dated April 14, 1896.

Application filed May 15, 1894. Serial No. 511,359. (No model.)

To all whom it may concern.-

Be it known that 1, WILLIAM R. COLE, a citizen of the United States, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Telephone-Transmitters, of which the following is a specification, reference being had therein to the accompanying drawings.

My improvement relates to that form of transmitting-telephone in which the variations in the strength of an electric current employed for reproducing sounds in a receiving instrument are produced by varying the resistance of the circuit by the variation in the pressure between contacts or what are called electrodes of the circuit. In the present construction of such contact-telephones changes in pressure are produced by the vibration of the diaphragm against two electrodes held in contact with each other and with the diaphragm by what I call for the purpose of this specification a dead resistance, such as produced by gravity, inertia, or the tension of a spring.

My invention consists, broadly, in substituting inpart for the dead resistance an active resistance developed or produced by manifestations of energy of the current itself and corresponding in character to the variations in pressure produced by the vibrations of the diaphragm for the purpose of inorea. in g the scope and amplitude of the variations or changes in the current, all as more fully hereinafter set forth.

In the accompanying drawings, Figure 1 is a perspective View of my telephone-transmitter, showing the door of the casing opened to disclose the mechanism. Fig. 2 is a vertical central section through the door and the mechanism supported thereon. Fig. 3 is a hori zontal section on line 00 :20, Fig. 2.

A represents the usual box or casing in which the mechanism is inclosed and attached to the cover A", which has the usual orifice A for speaking into.

B represents the diaphragm ,which is formed, as usual, of a thin iron plate and secured to the cover in the usual manner with its center opposite to the center of the orifice. On

the other side of the diaphragm, at its center, is placed the inner electrode 0, which in turn is in contact with the outer electrode D, both electrodes being of the usual character. The outer electrode is carried by an adj ustingscrew E in a recess F formed in the pole-piece G of an electromagnet H, which is suspended free to oscillate and, as will be seen, is free of all opposing forces other than the static force of gravity.

The pole-piece G has its inner face in which the recess F is formed in close proximity to the diaphragm and such proximity can be increased or decreased byprojecting or retracting the screw E, which carries the outer electrode, a lock-nut I being provided to lock the screw in its adjusted position.

The electromagnet is suspended in a manner to exert any desired static pressure against thecenter of the diaphragm. This may be accomplished by the devices shown in the drawings, in which J is ayoke rigidly secured to the upper end of the core and engaging with its free ends into Vertical guide-slots formed in the fixed guide-bar K, suitable shoulders or flanges L being formed on the free ends of the yoke to prevent endwise displacement while permitting a free vertical play in the guide-slots. The yoke passes freely through guide-slots M, formed in a support N in such a manner that the support forms the fulcrum upon which the yoke is free to oscillate with the magnet.

The support N is carried by an adjustingscrew 0, which passes through the door and is screw-threaded into the support, all so arranged that the screw may be operated from the outside of the box and serve as a means for adjusting the fulcrum of the yoke, and one or more guides P may be provided for the support N to prevent it from turning with the screw 0.

R represents the usual induction-coil, S the battery in circuit with the primary R',.and T net and is electrically connected to the other terminal of the primary.

The parts being thus constructed, as shown and described, it will be seen that a dead pressure is exerted by the weight of the magnet, the center of gravity of which overhangs the fulcrum of the yoke and presses the outer electrode against the inner one and against the diaphragm, thereby producing by the vibrations of the diaphragm the well-known Variations in the strength of the current employed for reproducing sounds.

It will be observed that when the term free is employed in designating the movement of the electrodes that I mean a movement which is unopp'osed byany magnetic force or spring-pressure during the vibrations of the diaphragm, the only opposing pressure being the natural static pressure 01' force of gravity, which is comparatively slight.

By means of the screw 0 the yoke can be adjusted, thereby altering the fulcrum from which the magnet is suspended and consequently increasing or decreasingits dead pressure against the electrodes. In addition to this dead pressure the magnet exerts an active pressure, which is derived from manifestations of energy of the current itself in passing through the coil H, thereby energizing the magnet and producing magnetic attraction between the pole G and diaphragm B with corresponding pressure between the electrodes. This magnetic attraction obviously fluctuates synchronously with the current which produces it, and its scope is greatly increased by the varying proximity between the diaphragm and pole of the magnet, as it will be seen that with the increase in current the distance between pole and diaphragm decreases, thus increasing the magnetic attraction, and correspondingly the magnetic attraction is decreasing as the distance increases on the decrease of the current. As the pole of the magnet can be adjusted from or toward the diaphragm by the screw E, the active pressure produced by the magnetic attraction can be adjusted within any desired limits.

In considering the difference between a dead and an active pressure as employed by me it must be understood that dead pressure, no matter how it is produced, must be more or less of an impediment to the free vibrations of the diaphragm and therefore is liable to fail to produce corresponding electric vibrations for the lesser or more delicate airvibrations caused by sound, and is also liable for well-understood reasons to cause more or less of a break between the electrodes, while the active pressure or resistance employed by me causes no impediment at all in the vibrations of the diaphragm, as it is merely a mutual attraction between the diaphragm and the pole of the magnet.

Broadly speaking, my invention consists in using only suihcient dead pressure to produce variations in the current and then increase the scope and amplitude of the variations by an active pressure produced by manifesta tions of energy of the current itself and corresponding in character to the variations in pressure produced by the vibrations of the diaphragm.

What I claim as my invention is 1. In a telephone-transmitter of the character described a suspended oscillatory electromagnet in the circuit of the transmitter and carrying the outer electrode, substantially as described.

2. In a telephone-transmitter of the character described and provided with a diaphragm of magnetic material, a suspended oscillatory electromagnet provided with a pole in attractive proximity to' the center of the diaphragm and carrying an electrode adj ustably mounted thereon, substantially as described.

In a telephone-transmitter, the combination with the diaphragm and the outer and inner electrodes in the circuit of the transmitter, of a suspended oscillatory electromagnet in the circuit of the transmitter carrying the outer electrode and operating by weight and magnetic attraction to produce changes in pressure between the electrodes by the vibrations of the diaphragm, substantially as described.

4. In a telephone-transmitter, the combina: tion of the diaphragm B, the outer and inner electrodes, the electromagnet the circuit ineluding said electrodes and electromagnet, the pole-piece of the electromagnet in attractive proximity centrally of the diaphragm and carrying the outer electrode, and a fulcrum suspending an oscillatory electromagnet between its center of gravity and the diaphragm, substantially as described.

5. In a telephone-transmitter of the character described the combination with the diaphragm and the electrodes in the circuit of the transmitter, of the eleetromagnet carrying the outer electrode, the yoke J laterally projecting from the electromagnet, the guidebar K in which the ends of the yoke are vertically guided, the supporting-bar N upon which the yoke J is fulcrumed and the adjusting-screw O of the supportingbar, substantially as described.

6. In a telephone-transmitter of the character described, the combination of the elec trodes in the circuit of the transmitter, of an oscillatory suspended electromagnet having its coil in the circuit of the transmitter, the pole G of the electromagnet, the diaphragm adapted to be magnetically attracted by said pole, the electrode D carried in a recess of the pole and resting against the inner electrode and the adj usting-screw E all arranged to operate substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

\VILLIAM R. COLE.

\Vitnesses:

M. B. ODoennn'rr, O. F. BARTHEL. 

